Multiuse optical sensor

• US 9,304,202 B2
• Filed: 05/20/2010
• Issued: 04/05/2016
• Est. Priority Date: 05/27/2009
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Deliwala, Shrenik
• Primary Examiner(s): LaBalle, Clayton E
• Assistant Examiner(s): Chang, Fang-Chi
• Application Number:
  US12/783,673
• Publication Number:
  US 20100305418A1
• Time in Patent Office: 2,147 Days
• Field of Search: 600/324, 600/310
• US Class Current: 1/1
• CPC Class Codes: A61B 5/02108 from analysis of pulse wave characteristics
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/486 Bio-feedback A61B5/375 takes precedence
• CPC Class Codes: A61B 5/684 Indicating the position of the sensor on the body
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• CPC Class Codes: G01S 17/06 Systems determining position data of a target
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 3/783 using amplitude comparison of signals derived from static detectors or detector systems
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves

Abstract

One or more electromagnetic radiation sources, such as a light emitting diode, may emit electromagnetic waves into a volume of space. When an object enters the volume of space, the electromagnetic waves may reflect off the object and strike one or more position sensitive detectors after passing through an imaging optical system such as glass, plastic lens, or a pinhole located at known distances from the sources. Mixed signal electronics may process detected signals at the position sensitive detectors to calculate position information as well as total reflected light intensity, which may be used in medical and other applications. A transparent barrier may separate the sources and detectors from the objects entering the volume of space and reflecting emitted waves. Methods and devices are provided.

Claims

1. A device comprising:

a source emitting electromagnetic radiation through a transparent barrier;

a position sensitive detector behind a first side of the barrier measuring a position and intensity of the electromagnetic radiation reflected off a body part of an organism placed on a surface of a second side of the barrier, the source modulated to reduce an effect of ambient radiation on the measurement; and

electronics to calculate (a) a position of the body part on the surface of the barrier based on the position of the measured reflected radiation and (b) a photoplethysmograph from changes to the reflected light intensity;

wherein the position sensitive detector measures the position of the reflected electromagnetic radiation by generating first and second currents at first and second ends, respectively, of the position sensitive detector, the first and second currents varying depending on a light distribution of the reflected electromagnetic radiation on a surface of the position sensitive detector facing the first side of the barrier.

2. The device of claim 1, wherein the calculated position of the body part updates as the body part is moved.

3. The device of claim 1, wherein the electronics further calculate a heart rate of the organism from the photoplethysmograph.

4. The device of claim 3, wherein the electronics are configured to instruct a user where to move the body part to improve the reflected light intensity.

5. The device of claim 1, further comprising a plurality of sources, each emitting electromagnetic radiation having a unique wavelength, the sources modulated to identify the source of reflected radiation at the detector.

6. The device of claim 5, wherein the wavelength of the radiation from a first source is around 660 nm and the wavelength of the radiation from a second source is around 900 nm.

7. The device of claim 5, wherein the electronics further calculate a measure of oxygenation.

8. The device of claim 1, wherein the device is a computing device.

9. The device of claim 8, wherein the computing device is portable.

10. The device of claim 9, wherein the computing device is a personal digital assistant.

11. The device of claim 1, wherein the electronics determine that higher levels of scattered light correspond to greater pressure applied by the body part.

12. The device of claim 11, further comprising a user interface, and wherein at least one of:

a degree of zooming and highlighting performed on the user interface, indicates a level of pressure exerted on the user interface.

13. The device of claim 1, wherein the source emits the electromagnetic radiation in at least two different wavelengths, and the electronics calculate the photoplethysmograph for each one of the different wavelengths.

14. The device of claim 1, wherein the barrier includes one of a focusing lens and an aperture.

15. The device of claim 14, wherein one of a focusing lens and an aperture is located in the barrier and adjacent to the surface on the second side of the barrier.

16. The device of claim 1, wherein one of a focusing lens and an aperture is located between the barrier and the position sensitive detector on the first side of the barrier.

17. The device of claim 1, wherein the electronics further calculate one of a heart rate and a blood oxygen content.

18. The device of claim 1, wherein the position sensitive detector measures the position of the reflected electromagnetic radiation by generating, in addition to the first and second currents, a third current and a fourth current at third and fourth ends, respectively, of the position sensitive detector, the third and fourth currents varying depending on a light distribution of the reflected electromagnetic radiation on a surface of the position sensitive detector facing the first side of the barrier.

19. A method comprising:

emitting electromagnetic radiation from a source through a transparent barrier;

reflecting the emitted radiation off a body part of an organism placed on a surface of a first side of the barrier;

detecting a position and intensity of the reflected radiation at a position sensitive detector behind a second side of the barrier;

modulating the radiation to reduce an effect of ambient radiation on the detection;

calculating a position of the body part on the surface from the detected position of the reflected radiation; and

calculating a photoplethysmograph from changes to the reflected radiation intensity;

wherein the position sensitive detector measures the position of the reflected electromagnetic radiation by generating first and second currents at first and second ends, respectively, of the position sensitive detector, the first and second currents varying depending on a light distribution of the reflected electromagnetic radiation on a surface of the position sensitive detector facing the first side of the barrier.

20. The method of claim 19, further comprising:

emitting electromagnetic radiation from a plurality of sources having unique wavelengths through the transparent barrier, the sources modulated to identify the sources of reflected radiation at the detector;

comparing the reflected radiation intensities from each source; and

calculating a measure of oxygenation from the comparison.

21. The method of claim 20, wherein the modulation of the sources includes modulation in one of a frequency domain and a time domain.

22. The method of claim 19, further comprising focusing, by one of a focusing lens and an aperture, the reflected radiation on the position sensitive detector.

23. The method of claim 19, further comprising calculating one of a heart rate and a blood oxygen content from changes to the reflected radiation intensity.

24. A device comprising:

means for emitting electromagnetic radiation through a transparent barrier;

means for measuring, from behind a first side of the barrier, a position and intensity of the electromagnetic radiation reflected off a body part of an organism placed on a surface of a second side of the barrier; and

means for calculating (a) a position of the body part on the surface of the barrier based on the position of the measured reflected radiation and (b) a photoplethysmograph from changes to the reflected light intensity;

wherein the means for measuring the position of the reflected electromagnetic radiation includes a step for generating first and second currents, the first and second currents varying depending on a light distribution of the reflected electromagnetic radiation on a surface of means for measuring the position of the reflected electromagnetic radiation facing the first side of the barrier, and

wherein the means for emitting electromagnetic radiation through a transparent barrier further includes means for modulating to reduce an effect of ambient radiation on the measurement.

25. The device of claim 24, wherein the means for calculating updates the calculation as the body part is moved.

26. The device of claim 24, wherein the means for calculating further calculates a heart rate of the organism from the photoplethysmograph.

27. The device of claim 24, wherein the means for emitting electromagnetic radiation emits a plurality of wavelengths of electromagnetic radiation, each having a unique wavelength.

28. The device of claim 27, wherein the means for emitting electromagnetic radiation emits one of the plurality of wavelengths of electromagnetic radiation.

29. The device of claim 27, wherein the means for emitting electromagnetic radiation modulates the plurality of wavelengths of electromagnetic radiation to identify a source of reflected radiation at the detector.

30. The device of claim 24, wherein a wavelength of the electromagnetic radiation emitted from the means for emitting electromagnetic radiation is around 660 nm or around 900 nm.

31. The device of claim 24, wherein the means for calculating further calculates a measure of oxygenation.

32. The device of claim 24, wherein the means for calculating is configured to instruct a user where to move the body part to improve the reflected light intensity.

33. The device of claim 24, wherein the device is a computing device.

34. The device of claim 33, wherein the computing device is portable.

35. The device of claim 34, wherein the computing device is a personal digital assistant.

36. The device of claim 24, wherein the means for calculating determines that higher levels of scattered light correspond to greater pressure applied by the body part.

37. The device of claim 36, the device further comprising means for interfacing with the device, and wherein at least one of:

a degree of zooming and highlighting performed on the means for interfacing with the device, indicates a level of pressure exerted by the body part.

38. The device of claim 24, further comprising means for calculating one of a heart rate and a blood oxygen content from changes to the reflected radiation intensity.

39. The device of claim 24, further comprising means for focusing the reflected radiation on the means for measuring the position of the reflected electromagnetic radiation.

40. The device of claim 24, wherein the means for measuring the position of the reflected electromagnetic radiation includes means for generating, in addition to the first and second currents, a third current and a fourth current, the third and fourth currents varying depending on a light distribution of the reflected electromagnetic radiation on a surface of the means for measuring the position of the reflected electromagnetic radiation facing the first side of the barrier.